This application is related to Japanese Patent Applications No. 2001-206683 filed on Jul. 6, 2001, and No. 2002-150786 filed on May 24, 2002, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an ejector cycle system having an improved refrigerant passage structure.
2. Description of Related Art
In an ejector cycle System described in JP-A-6-11197, an ejector sucks gas refrigerant evaporated in an evaporator at a low pressure side, and increases a pressure of refrigerant to be sucked into a compressor by converting an expansion energy to a pressure energy. In the ejector cycle system, refrigerant discharged from the ejector flows into a gas-liquid separator, so that liquid refrigerant separated in the gas-liquid is supplied to the evaporator, and gas refrigerant separated in the gas-liquid separator is sucked into the compressor. Accordingly, the refrigerant cycle system has a refrigerant flow circulating through the compressor, a radiator, the ejector, the gas-liquid separator and the compressor in this order, and a refrigerant flow circulating through the gas-liquid separator, the evaporator, the ejector and the gas-liquid separator in this order. In the ejector cycle system, the evaporator may be frosted sometimes, and it is necessary to defrost the evaporator. However, in the ejector cycle system, it is impossible to perform defrosting operation of the evaporator.
In view of the foregoing problems, it is an object of the present invention to provide an ejector cycle system having an improved refrigerant passage structure.
It is an another object of the present invention to provide an ejector cycle system which can substantially perform a defrosting operation of an evaporator.
It is a further another object of the present invention to provide an ejector cycle system which can shorten a defrosting time period.
According to the present invention, an ejector cycle system includes a compressor for sucking and compressing refrigerant, a radiator which cools refrigerant discharged from the compressor, an evaporator for evaporating the refrigerant to obtain cooling capacity, a gas-liquid separator having a gas refrigerant outlet coupled to a refrigerant suction side of the compressor and a liquid refrigerant outlet coupled to a side of the evaporator, and an ejector. The ejector includes a nozzle for converting a pressure energy of high-pressure refrigerant from the radiator to a speed energy so that the high-pressure refrigerant is decompressed and expanded, and a pressure-increasing portion in which the speed energy is converted to the pressure energy so that the pressure of refrigerant is increased while refrigerant discharged from the nozzle and gas refrigerant from the evaporator are mixed. In the ejector cycle system, refrigerant discharged from the compressor is introduced into the evaporator while bypassing the ejector and the gas-liquid separator, in a defrosting operation for defrosting frost generated on the evaporator. Accordingly, it can prevent liquid refrigerant in the gas-liquid separator from flowing into the evaporator in the defrosting operation. Therefore, the defrosting operation can be effectively performed, and a defrosting time period for which the defrosting operation is performed can be made shorter. That is, the ejector cycle system has an improved refrigerant passage structure for performing the defrosting operation of the evaporator.
Preferably, a pressure-loss generating unit for generating a predetermined pressure loss is disposed in a refrigerant passage through which the liquid refrigerant outlet of the gas-liquid separator communicates with the evaporator. For example, the pressure-loss generating unit is a throttle member, or a valve which adjusts an opening degree of the refrigerant passage to generate a predetermined pressure loss in the refrigerant passage. Therefore, hot gas refrigerant discharged from the compressor can be accurately flows into the evaporator through a bypass passage without flowing toward the gas-liquid separator.
Preferably, a check valve is disposed in the refrigerant passage through which the liquid refrigerant outlet of the gas-liquid separator communicates with the evaporator, to prohibit a refrigerant flow from the evaporator toward the gas-liquid separator through the refrigerant passage. Therefore, the defrosting operation of the evaporator can be accurately performed using hot gas refrigerant introduced into the evaporator through the bypass passage.
Further, an another gas-liquid separator is disposed in a refrigerant passage connecting the evaporator and the ejector, and has a refrigerant outlet from which the gas refrigerant separated in the another gas-liquid separator is sucked into the ejector. Therefore, hot gas refrigerant from the compressor is introduced into the evaporator through the bypass passage in the defrosting operation to heat the evaporator so that refrigerant (liquid refrigerant) staying in the evaporator is discharged outside the evaporator. In this case, liquid refrigerant among the refrigerant flowing from the evaporator stays in the another gas-liquid separator, and gas refrigerant separated in the another gas-liquid separator is sucked into the ejector. Thus, operation of the ejector cycle system with the ejector can be effectively performed.